On August 8, 2004, at 1330 eastern daylight time, a homebuilt Mustang II, N91061, was substantially damaged during a forced landing in Rainelle, West Virginia. The certificated airline transport pilot was seriously injured. Visual meteorological conditions prevailed for local personal flight that originated at Rainelle Airport, Rainelle, West Virginia, at 1325. No flight plan was filed for the flight conducted under 14 CFR Part 91. During a telephone interview, the pilot reported that after takeoff he intended to fly a low pass down runway 35 prior to departing the traffic pattern. The takeoff and initial climb to the downwind leg of the traffic pattern were routine, and the pilot reduced power to arrest his climb and begin a descent through the base and final legs of the pattern. He estimated that his power setting was between 700 and 1,000 rpm after the power reduction. Once established on the final approach, the pilot perceived that his approach angle was too shallow, and pushed the throttle forward to re-intercept his desired glide path. There was no response from the engine, and actuation of the fuel boost pumps, carburetor heat, and the fuel selector valve failed to restore control of the engine. However, the engine continued to run at 700 to 1,000 RPM. The pilot determined that he couldn't reach the runway, which was on a hilltop, and turned down a valley adjacent to the airport in search of a forced landing area. He over flew several fields due to large bales of hay obstructing the landing surface, and selected an open field about 1 to 2 miles northeast of the airport. The pilot selected an approach path between two trees that bordered the field. On short final, he noticed a dead tree with no foliage in his path, but determined that his altitude and airspeed were too low to maneuver around it. The airplane struck the tree, contacted the ground, spun around, and came to rest facing opposite the direction of travel. A West Virginia Army National Guard MEDEVAC helicopter overheard the pilot's radio calls, landed at the crash site, and transported the pilot to a local hospital for treatment. Examination of the airplane at the scene by Federal Aviation Administration (FAA) aviation safety inspectors revealed that the engine and its associated controls were almost completely separated from the airplane during the crash sequence. Follow-up examination by the inspectors revealed a separation of the throttle cable outer sheath and the inner throttle cable. When forward movement was applied to the throttle control, the inner cable bowed, and did not transfer forward motion to the throttle arm. The pilot reported that other than the loss of engine control, there were no anomalies of note. According to FAA Advisory Circular AC-20-27D, Certification and Operation of Amateur-Built Aircraft: "...FAA inspections of amateur-built aircraft have been limited to ensuring the use of acceptable workmanship methods, techniques, practices, and issuing operating limitations necessary to protect persons and property not involved in this activity." The weather reported at Lewisburg, West Virginia, 16 miles northwest of Rainelle, at 1337, included winds from 190 degrees at 5 knots, 10 statute miles visibility, scattered clouds at 5,000 feet, temperature 68 degrees Fahrenheit, dew point 55 degrees Fahrenheit, and a barometric pressure of 30.22 inches of mercury.